Renaming files with Node.js

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In my last post, I presented how to change the names of files in a directory using Python. That's very useful if we have a lot of files and we want to rename every single one. Now I would like to show how to achieve the same goal using a different programming language. This time it's JavaScript (Node JS).

Generating files

First, let's create a directory with files to work with. It will imitate the situation where we have a lot of files to modify. Basically, I need to use the fs (filesystem) built-in module which should be available in any Node version. In this example, my version of node is 14.18.


const fs = require('fs');
const folderPath = './filename_changer';
const filesNum = 100;

for (let i = 0; i < filesNum; i++) {
  fs.writeFile(`${folderPath}/${Math.random().toString(36).substr(2, 10)}.txt`, `This is file number ${i}`, (err) => {
    if (err) throw err;
    console.log('File created', i)

That's it. This will generate 100 .txt files in a given directory. Files will have a name with random letters and digits sequence. To run this script you have to save it in one directory up to a folder you would like to modify and then run it through a terminal using the command node generateFiles.js. For the purpose of this exercise, I put all my files in a filename_changer directory. Of course, you can run this script from any other place, you just have to modify the folderPath variable and adjust to your folder structure.

Renaming files

This operation requires creating an array with all files from a directory. Then we have to loop through it and rename each of the files, giving them the desired name.


const fs = require('fs');
const folderPath = './filename_changer';

files.forEach((file, idx) => {
  fs.rename(`${folderPath}/${file}`, `${folderPath}/new_file_${idx}.txt`, function(err) {
    if ( err ) console.log('ERROR: ' + err);